The present invention relates to a new water treatment device capable of sterilizing water stored in various types of pools from large-sized pools such as a swimming pool and a bathtub of a public bath to small-sized pools such as a water supply tank disposed on the roof of a building or the like and a home bathtub.
The swimming pool which is installed indoors or outdoors, or the bathtub of the public bath, for example, must be subjected to sterilization by periodically introducing chlorinated lime, sodium hypochlorite (NaClO), or the like into the water in order to maintain the quality of the water.
However, it has been conventionally necessary for employees in facilities, for example, to perform the work by hand outside the business hours (early in the morning, at midnight, etc.), and moreover, the operation had to be done with great caution since the chlorinated lime or sodium hypochlorite are irritant.
Chlorinated lime is generally in the shape of powder or a shape of a tablet obtained by solidifying the powder. Accordingly, it takes a long time until the chlorinated lime is dissolved to make the concentration thereof uniform after it is introduced into the pool. During the time, the pool cannot be used.
In the case of the water supply tank disposed on the roof of the building or the home bathtub, it depends on only a sterilizing force of chlorine contained in tap water. Particularly in the case of the water supply tank, algae reproduces inside thereof, resulting in degraded water quality.
In the case of the home bathtub, the water is generally exchanged every one or two days, so that it tends to be considered that there is no problem in terms of the water quality. However, the inside of a boiler connected to the bathtub cannot be frequently cleaned. Therefore, various types of germs, mold, and so forth are liable to reproduce. Accordingly, it is feared that the water quality is degraded.
When the water stored in each of the above-mentioned pools is sterilized, the residual chlorine concentration of the water must be in a predetermined range depending on the applications of the pool and the water.
The residual chlorine concentration can be measured using a residual chlorine sensor. In the case of the large-sized pool such as the swimming pool or the public bath, a time lag occurs between the average residual chlorine concentration in the pool and the concentration measured by the residual chlorine sensor.
Specifically, it takes a long time until the residual chlorine concentration in the pool is averaged after chlorinated lime or sodium hypochlorite is introduced into the pool. Even if the residual chlorine concentration is measured by the residual chlorine sensor in a particular place, therefore, a correct measured value cannot be obtained. Accordingly, it takes a long time until the correct measured value can be obtained.
A first object of the present invention is to provide a new water treatment device capable of simply and efficiently sterilizing water stored in various types of pools, described above.
A second object of the present invention is to provide a water treatment device capable of satisfactorily measuring the residual chlorine concentration of water and automatically maintaining the concentration in a desired range with a good response.
The invention as set forth in the claim 1 is directed to a water treatment device comprising electrolyzing and sterilizing means, comprising an electrolytic tank to put water in and an electrode provided in the electrolytic tank in order to electrolyze the water, for pouring water into the electrolytic tank to energize the electrode, and electrolyzing the water, to sterilize the water; a water treating path connected to a pool storing water for pouring the water in the pool into the electrolytic tank and returning to the pool the water in the electrolytic tank; a residual chlorine sensor for measuring the residual chlorine concentration of water; and control means for controlling the energization of the electrode on the basis of the measured value by the residual chlorine sensor.
In the construction as set forth in the claim 1, the electrode arranged in the electrolytic tank is energized in a state where an electrolyte containing chlorine such as sodium chloride (NaCl), calcium chloride (CaCl2), or hydrochloric acid (HCl) is added to the water which has been poured into the electrolytic tank through the water treating path from the pool or a state where no electrolyte is added when the water previously contains an electrolyte for sterilization.
Consequently, the water is sterilized by a chlorine compound such as hypochlorous acid (HClO), its ion (CLOxe2x88x92), or chlorine gas (Cl2) which is generated by electrolytic reaction, described below, active oxygen (O2xe2x88x92) generated for a very short time in the reaction process, or the like, and is then returned to the pool through the water treating path.
(Anode)
4H2Oxe2x88x924exe2x88x92xe2x86x924H+O2↑+2H2O
2Clxe2x88x92xe2x86x92Cl2+2exe2x88x92
H2O+Cl2⇄HClO+H++Clxe2x88x92
(Cathode)
4H2O+4exe2x88x92xe2x86x922H2↑+4OHxe2x88x92
(Anode+Cathode)
H++OHxe2x88x92xe2x86x92H2O
The above-mentioned series of operations is performed only by a worker operating a pump for circulating the water through the water treating path and energizing the electrode without almost passing through human hands or without the worker directly touching the water. If the operation of the pump, the energization of the electrode, or the like is automated utilizing a timer or a residual chlorine sensor, the water treatment can be completely automated.
Therefore, in the construction as set forth in the claim 1, the water stored in the pool can be simply and efficiently sterilized.
Moreover, the water returned to the pool upon being sterilized by the water treatment device contains only ions having a significantly low concentration. Accordingly, the above-mentioned treatment can be performed periodically even during the business hours of the swimming pool, the public bath, or the like or arbitrarily in accordance with the quality of the water which varies depending on the number of visitors, the weather, the temperature, or the like.
In the swimming pool, the public bath, or the like, therefore, work for introducing chlorinated lime, sodium hypochlorite, or the like to sterilize the water can be entirely omitted, or the number of times of the work can be significantly reduced. Accordingly, the water quality can be kept good while significantly easing the burden on the worker.
In the water supply tank disposed on the roof of the building, for example, the series of work is manually or automatically performed for each predetermined volume of used water, for example, or for each predetermined time period irrespective of the volume of used water, it is possible to prevent the water quality from being degraded by restraining the reproduction of algae.
Furthermore, in the home bathtub or the like, the series of work is manually or automatically performed at the time point where daily bathing is terminated, for example, and prior to draining bath water, it is possible to prevent the water quality from being degraded by restraining the reproduction of germs, mold, or the like in a boiler connected to the bathtub.
In the construction as set forth in the claim 1, the correlation of the amount of free residual chlorine generated by electrolysis with the amount of applied current (the amount of charge) is utilized, to find a difference between the residual chlorine concentration measured by the residual chlorine sensor and the required residual chlorine concentration previously determined, and find an insufficient amount of residual chlorine from the difference and the quantity of water stored in the pool. Current in an amount required to produce the insufficient amount of chlorine by the electrolysis is supplied to the electrode, thereby making it possible to control the residual chlorine concentration not uselessly.
Therefore, in the construction as set forth in the claim 1, the energization is automatically controlled on the basis of the measured value by the residual chlorine sensor, thereby making it possible to maintain the residual chlorine concentration of the water in a predetermined range with high precision.
The invention as set forth in the claim 2 is the water treatment device as set forth in the claim 1, further comprising setting means for setting the residual chlorine concentration of the water, the control means controlling the energization of the electrode such that the measured value by the residual chlorine sensor is equal to the residual chlorine concentration set by the setting means.
In the construction as set forth in the claim 2, when a user sets the residual chlorine concentration by the setting means, the energization of the electrode is automatically controlled such that the residual chlorine concentration of the water is equal to the set concentration.
Therefore, in accordance with the water quality of the water which varies depending on the number of visitors of the pool such as the swimming pool or the public bath, the weather, the temperature, or the like, the residual chlorine concentration of the water in the pool can be arbitrarily controlled. The residual chlorine concentration of the water can be set to a desired concentration depending on the type, that is, the applications of the pool to which the water treatment device is applied, thereby making it possible to make the water treatment device applicable to various types of pools.
The invention as set forth in the claim 3 is the water treatment device as set forth in the claim 1, further comprising temperature sensing means for measuring the temperature of the water in the electrolytic tank, the control means controlling the energization of the electrode on the basis of an output of the temperature sensing means.
In the construction as set forth in the claim 3, it is possible to safely and most suitably sterilize the water in the ranges of the heat-resistant temperatures of the electrolytic tank and the water treating path.
In supplying current to the electrode in the electrolyzing and sterilizing means to sterilize the water, when the supplied current is abnormally increased or the quantity of the water poured into the electrolytic tank is abnormally decreased, the temperature of the water in the electrolytic tank may be abnormally raised. Particularly when the electrolytic tank and the water treating path are formed of a resin material such as polyvinyl chloride, the heat-resistant temperatures are not high. Therefore, measures must be taken.
In the construction as set forth in the claim 3, the temperature is always sensed by the temperature sensing means. When the temperature is increased, the energization of the electrode is reduced or stopped, thereby making it possible to sterilize the water in the safe temperature range.
The invention as set forth in the claim 4 is the water treatment device as set forth in the claim 3, wherein the control means controls the pouring of the water into the electrolytic tank on the basis of the output of the temperature sensing means.
In the construction as set forth in the claim 4, when the temperature sensed by the temperature sensing means rises, the quantity of the water poured into the electrolytic tank is increased, to shorten a time period during which the water stays in the electrolytic tank, thereby making it possible to prevent the temperature of the water in the electrolytic tank from rising.
The invention as set forth in the claim 5 is the water treatment device as set forth in the claim 1, further comprising gas/liquid separating means for separating from the water gas generated by the electrolysis in the electrolyzing and sterilizing means, and gas separation sensing means for sensing circumstances where the gas is separated in the gas/liquid separating means, the control means controlling the energization of the electrode on the basis of an output of the gas separation sensing means.
In the construction as set forth in the claim 5, it is possible to safely remove gas containing combustible hydrogen which is generated by the above-mentioned electrolytic reaction and included into the water and is separated by the gas/liquid separating means.
As a specific example of the gas separation sensing means, the construction as set forth in the claim 6 or 7 is employed.
The invention as set forth in the claim 6 is the water treatment device as set forth in the claim 5, wherein the gas separation sensing means senses the concentration of hydrogen contained in the separated gas.
In the construction as set forth in the claim 6, gas is prevented from being further generated by restraining or stopping the energization of the electrode when the concentration of hydrogen in the gas separated by the gas/liquid separating means is increased by any abnormality, thereby making it possible to prevent hydrogen gas from being ignited.
The invention as set forth in the claim 7 is the water treatment device as set forth in the claim 5, further comprising exhausting means for exhausting the gas separated from the water in the gas/liquid separating means, the gas separation sensing means being exhaust sensing means for sensing circumstances where the gas is exhausted by the exhausting means.
In the construction as set forth in the claim 7, gas is prevented from being further generated by stopping the energization of the electrode in cases such as a case where the exhausting means develops a fault, thereby making it possible to prevent hydrogen gas from being ignited.
The invention as set forth in the claim 8 is the water treatment device as set forth in the claim 1, wherein two or more pairs of electrodes are provided in the electrolytic tank such that the energization can be performed independently for each of the pairs of electrodes, and the control means controls the energization by changing the number of pairs of electrodes to be simultaneously energized.
In the construction as set forth in the claim 8, the sterilizing capability of the water treatment device can be arbitrarily adjusted in accordance with the water quality of the water in the pool which varies depending on the number of visitors, the weather, the temperature, or the like.
When the number of visitors is rapidly increased during the business hours of the swimming pool or the public bath, the number of pairs of electrodes to be simultaneously energized is increased to enhance the sterilizing capability, thereby making it possible to keep the water quality approximately constant. On the other hand, when the number of visitors is small, the number of pairs of electrodes to be simultaneously energized is decreased, thereby making it possible to restrain power to be consumed.
Furthermore, the pairs of electrodes are alternately rested, thereby making it possible to prevent the electrodes from being deteriorated. That is, a scale mainly composed of calcium, magnesium, its oxide or hydroxide produced by electrolytic reaction from a calcium ion (Ca2+) or a magnesium ion (Mg2+) contained in water, is gradually deposited on a surface of the electrode that is a cathode. On the other hand, a surface of the electrode that is an anode is gradually eroded by sodium hypochlorite or active oxygen.
When a plurality of pairs of electrodes are alternately employed without continuously employing only one pair of electrodes, that is, one of the pairs of electrodes is employed, during which the other pairs of electrodes are rested, the electrode can be kept for a long time by preventing the deterioration thereof.
The invention as set forth in the claim 9 is the water treatment device as set forth in the claim 1, wherein a pair of electrodes is provided in the electrolytic tank, and the control means reverses the polarity of a voltage to be supplied to the pair of electrodes for each predetermined time period.
The scale is deposited, as described above, on the surface of the electrode that is the cathode in the pair of electrodes, so that the electrolyzing capability is gradually lowered. As a result, the sterilization efficiency tends to be gradually decreased.
Contrary to this, in the construction as set forth in the claim 9, the polarity of the voltage to be supplied to the pair of electrodes is periodically reversed, so that the deposited scale can be removed from the surface of the electrode by being ionized again and dissolved. Accordingly, the sterilization efficiency can be always kept approximately constant by making the most use of the electrolyzing capability of the pair of electrodes.
The invention as set forth in the claim 10 is the water treatment device as set forth in the claim 9, further comprising setting means for setting the hardness of the water, the control means controlling the length of a time period during which the polarity of a voltage is reversed depending on the hardness of the water set by the setting means.
In the invention as set forth in the claim 10, the length of the time period elapsed until the polarity is reversed can be controlled depending on the hardness of the water for defining the concentration of a calcium ion or a magnesium ion which causes the scale. That is, when the hardness of the water is high, the time period elapsed until the polarity is reversed can be set to a short time period. Accordingly, the scale is efficiently removed irrespective of the hardness of the water, the difference between areas, or the like, thereby making it possible to always stably perform the sterilization.
The invention as set forth in the claim 11 is the water treatment device as set forth in the claim 1, wherein a first plate-shaped electrode and a second plate-shaped electrode are arranged parallel to each other in the electrolytic tank, one or more plate-shaped electrodes are arranged parallel to both the first and second electrodes between the electrodes, and wiring for energization is connected to the first and second electrodes.
In the construction as set forth in the claim 11, the wiring for energization is connected to only the first and second electrodes at both ends out of the plurality of plate-shaped electrodes. Accordingly, the wiring structure can be simplified, and the number of portions, pulled out of the electrolytic tank, of the wiring can be reduced. Therefore, the water-tightness of the wiring is improved, thereby making it difficult for the water to leak.
In this case, a voltage is applied to the electrodes at both ends, so that both two surfaces of the middle electrode are polarized. Accordingly, a potential difference corresponding to the voltage applied between the two electrodes at both ends divided by the number of clearances among the electrodes occurs between the middle electrode and the adjacent electrode. Therefore, the middle electrode can sufficiently function as an electrode for sterilizing the water by the above-mentioned electrolytic reaction as a so-called bipolar type electrode.
The invention as set forth in the claim 12 is the water treatment device as set forth in the claim 11, wherein three or more plate-shaped electrodes are arranged parallel to both the first and second electrodes between the electrodes, and wiring for energization is connected to the first and second electrodes and the electrodes located at intervals of a predetermined number of electrodes between the first and second electrodes.
In the construction as set forth in the claim 12, the wiring for energization is also connected to the electrodes located at intervals of a predetermined number of electrodes between the first and second electrodes at both ends in addition to the function as set forth in the claim 11. Particularly when the number of electrodes is large, the voltage drop in the bipolar type electrode to which the wiring is not connected between the electrodes to which the wiring is connected is restrained, thereby making it possible to efficiently sterilize the water.
The invention as set forth in the claim 13 is the water treatment device as set forth in the claim 11, wherein the first and second electrodes are arranged such that they respectively contact to an inner wall surface of the electrolytic tank.
In the construction as set forth in the claim 13, respective outer surfaces of the first and second electrodes at both ends on which the scale is most easily deposited are concealed with the surfaces contact to the inner wall surface of the electrolytic tank such that they are not brought into contact with the water in addition to the function as set forth in the claim 11, thereby making it possible to lengthen the life of the electrode.
Specifically, the respective inner surfaces of the first and second electrodes or both the two surfaces of the electrode between both the electrodes make it possible to ionize, dissolve, and remove the scale deposited on the surface again to some extent by reversing the polarity of an applied voltage. However, the respective outer surfaces of both the electrodes at both ends hardly relate to the electrolytic reaction. Moreover, even if the polarity is reversed, the scale cannot be effectively removed. Accordingly, it is most effective in preventing the scale from being deposited to conceal the outer surfaces of the first and second electrodes at both ends with the surfaces contacting to the inner wall surface of the electrolytic tank such that they are not brought into contact with the water.
The invention as set forth in the claim 14 is the water treatment device as set forth in the claim 1, further comprising sterilizing solution producing means, comprising a second electrolytic tank to put in an electrolytic solution containing a chlorine ion and a second electrode provided in the second electrolytic tank in order to electrolyze the electrolytic solution, for pouring the electrolytic solution into the second electrolytic tank to energize the second electrode, and electrolyzing the electrolytic solution to produce a sterilizing solution, and a supplying path for supplying to a water treating path the sterilizing solution produced by the sterilizing solution producing means.
In the construction as set forth in the claim 14, the sterilizing solution having a sterilizing function containing a chlorine compound such as hypochlorous acid, its ion, or chlorine gas which is generated by energizing the second electrode to electrolyze the electrolytic solution containing the chlorine ion in a state where the electrolytic solution is poured into the second electrolytic tank in the sterilizing solution producing means can be supplied to the water treating path through the supplying path.
Therefore, the chlorine ion concentration of the water poured into the electrolytic tank in the electrolyzing and sterilizing means is increased, thereby making it possible to improve the efficiency of the electrolytic reaction by the electrode in the electrolyzing and sterilizing means. Moreover, the sterilizing solution which is previously produced by energizing the second electrode and stored in the electrolytic tank in the sterilizing solution producing means is supplied to the water treating path on demand, thereby making it possible to arbitrarily adjust the processing capability of the device in accordance with the water quality of water which varies depending on the number of visitors, the weather, the temperature, or the like.
For example, even if the number of visitors is rapidly increased during the business hours of the swimming pool, the public bath, or the like, the water quality can be kept approximately constant.
The electrode in the electrolyzing and sterilizing means is rested when the number of visitors is small, thereby making it possible to prevent the electrode from being deteriorated.
The invention as set forth in the claim 15 is the water treatment device as set forth in the claim 14, wherein the control means energizes the second electrode in a time zone in which water is not sterilized by the electrolyzing and sterilizing means, to produce the sterilizing solution, stores the produced sterilizing solution in the second electrolytic tank, and supplies the sterilizing solution stored in the second electrolytic tank to the water treating path on demand through the supplying path in a time zone in which water is sterilized by the electrolyzing and sterilizing means.
In the construction as set forth in the claim 15, the sterilizing solution is produced by the sterilizing solution producing means by making use of a break time zone of the device, for example, nighttime hours, is stored in the second electrolytic tank, and is supplied to the water treating path on demand as the number of visitors increases, for example, during the business hours of the swimming pool, the public bath, or the like, thereby making it possible to assist in sterilizing the water by the electrolyzing and sterilizing means.
Therefore, the power consumption in a time zone such as daytime hours in the summer where power conditions are liable to be tight because there are the largest number of visitors particularly in the swimming pool, and the amount of electric power consumed by air conditioners or the like is increased is prevented from being increased, thereby making it possible to contribute to the stable utilization of power.
Moreover, cheap power at night is utilized, thereby making it possible to also reduce the running cost of the device.
The invention as set forth in the claim 16 is the water treatment device as set forth in the claim 1, wherein the control means pours the electrolytic solution containing a chlorine ion into the electrolytic tank in the electrolyzing and sterilizing means to energize the electrode in a time zone in which water is not sterilized by the electrolyzing and sterilizing means, and electrolyzes the electrolytic solution to produce the sterilizing solution.
In the construction as set forth in the claim 16, it is possible to produce the sterilizing solution by the electrolyzing and sterilizing means by making use of a break time zone of the device, for example, nighttime hours.
The water poured into the electrolytic tank through the water treating path while supplying the produced sterilizing solution to the pool through the water treating path is sterilized by energizing the electrode, thereby making it possible to more reliably and quickly perform the sterilization particularly at the time of starting the business hours of the swimming pool, the public bath, or the like.
In this case, the chlorine ion concentration of the water poured into the electrolytic tank is increased, thereby making it possible to also improve the efficiency of the electrolytic reaction by the electrode in the electrolyzing and sterilizing means.
The invention as set forth in the claim 17 is the water treatment device as set forth in the claim 16, comprising a sterilizing solution tank to put in the sterilizing solution produced by the electrolyzing and sterilizing means, a first supplying path for supplying the sterilizing solution to the sterilizing solution tank from the electrolytic tank, and a second supplying path for supplying the sterilizing solution to the water treating path from the sterilizing solution tank, the control means pouring the sterilizing solution produced in the electrolyzing and sterilizing means into the sterilizing solution tank through the first supplying path in a time zone in which water is not sterilized by the electrolyzing and sterilizing means, and the sterilizing solution stored in the sterilizing solution tank being supplied to the water treating path on demand through the second supplying path in a time period during which water is sterilized by the electrolyzing and sterilizing means.
In the construction as set forth in the claim 17, the sterilizing solution produced at night, for example, is stored in the sterilizing solution tank, and is supplied to the water treating path on demand as the number of visitors increases, for example, during the business hours of the swimming pool, the public bath, or the like in addition to the function as set forth in the claim 16, thereby making it possible to assist in sterilizing the water by the electrolyzing and sterilizing means.
As in the claim 15, the power consumption in a time zone such as daytime hours in the summer where power conditions are liable to be tight because there are the largest number of visitors particularly in the swimming pool, and the amount of electric power consumed by air conditioners or the like is increased is prevented from being increased, thereby making it possible to contribute to the stable utilization of power. Further, cheap power at night is utilized, thereby making it possible to reduce the driving cost of the device.
As the electrolytic solution used in the construction as set forth in the claims 14 to 17, a solution of common salt (sodium chloride) which is easily obtained and handled and is cheap is suitable.
The invention as set forth in the claim 18 is the water treatment device as set forth in the claim 1, further comprising a solution tank to put in an electrolytic solution containing a chlorine ion having a sterilizing function, and a supplying path for supplying the electrolytic solution poured into the solution tank to the electrolytic tank in the electrolyzing and sterilizing means, the control means supplying the electrolytic solution stored in the solution tank to the electrolytic tank on demand through the supplying path while sterilizing the water by the electrolyzing and sterilizing means.
In the construction as set forth in the claim 18, the electrolytic solution itself also functioning as the sterilizing solution can be supplied to the electrolytic tank on demand through the supplying path during the business hours of the swimming pool, the public path, or the like. Also in this case, the chlorine ion concentration in the electrolytic tank is increased, thereby making it possible to increase the efficiency of the electrolytic reaction by the electrode or arbitrarily adjust the processing capability of the device in accordance with the water quality of the water which varies depending on the number of visitors, the weather, the temperature, or the like.
Even if the number of visitors is rapidly increased during the business hours of the pool, for example, therefore, the water quality can be kept approximately constant. Moreover, the pair of electrodes is rested, when the number of visitors is small, thereby making it possible to also prevent the electrodes constituting the pair of electrodes from being deteriorated.
Furthermore, the power consumption in a time zone in which power conditions are liable to be tight is prevented from being increased, thereby making it possible to also contribute to stable utilization of power.
An example of the electrolytic solution used in the construction as set forth in the claim 18 is a solution of hypochlorite such as sodium hypochlorite.
The invention as set forth in the claim 19 is the water treatment device as set forth in the claim 1, further comprising pH sensing means for measuring the pH of water, an adjusting solution tank to put in a pH adjusting solution for adjusting the pH of water, and a supplying path for supplying to the water treating path the pH adjusting solution poured into the adjusting solution tank, the control means supplying the pH adjusting solution to the water treating path from the adjusting solution tank on demand through the supplying path to adjust the pH of the water on the basis of an output of the pH sensing means.
In the construction as set forth in the claim 19, the pH of the water can be adjusted by the pH adjusting solution supplied from the adjusting solution tank in a predetermined range (generally around 4.5) which is suitable for the electrolytic reaction, that is, in which the electrolytic reaction easily progresses when the electrode is energized, thereby making it possible to always maintain the efficiency of the sterilization at a high level irrespective of the water quality of the water.
In the public bath, for example, the pH of the water can be also adjusted to the range of the pH which has characteristics, for example, an acid bath or an alkaline bath.
The invention as set forth in the claim 20 is the water treatment device as set forth in the claim 19, comprising a first adjusting solution tank to put in an alkaline pH adjusting solution, a first supplying path for supplying to the water treating path the pH adjusting solution poured into the first adjusting solution tank, a second adjusting solution tank to put in an acid pH adjusting solution, and a second supplying path for supplying to the water treating path the pH adjusting solution poured into the second adjusting solution tank, the control means supplying the alkali and/or acid pH adjusting solution to the water treating path from the first or second adjusting solution tank on demand through the first or second supplying path on the basis of an output of the pH sensing means, to adjust the pH of the water. For example, when the water is acid water, and the target pH is neutral or alkaline, only the first adjusting solution tank and the first supplying path for the alkaline pH adjusting solution may be provided. When the water is alkaline water, and the target pH is neutral or acid, only the second adjusting solution tank and the second supplying path for the acid pH adjusting solution may be provided. In the construction as set forth in the claim 20 comprising both the tank and the supplying path, the pH of the water in the pool can be strictly maintained by the target value irrespective of the pH of raw material water and the target pH.
The invention as set forth in the claim 21 is the water treatment device as set forth in the claim 1, wherein the electrolytic tank comprises an inlet for pouring an acid serving as a cleaning solution, and an outlet for discharging a solution in the electrolytic tank.
In the construction as set forth in the claim 21, after an inorganic acid and/or an organic acid serving as a cleaning solution is poured from the inlet provided in the electrolytic tank as maintenance outside the business hours and on the closed days of the swimming pool, the public bath, or the like, to dissolve or strip the scale deposited mainly on the surface of the electrode in the electrolytic tank, the scale, together with the cleaning solution, can be discharged and removed from the outlet, thereby making it possible to lengthen the life of the whole system.
As described in the foregoing, the scale deposited on the surface of the electrode can be removed to some extent by reversing the polarity of the voltage applied to the electrode. However, the larger the number of times of the reverse of the polarity is, the shorter the life of the electrode tends to be made.
Contrary to this, the step of maintenance for removing the scale by the cleaning solution is interposed, thereby making it possible to reduce the number of times of the reverse of the polarity and lengthen the life of the electrode.
Particularly a hydroxide of calcium or magnesium is easily deposited as a scale in portions other than the electrode because the solubility in water is decreased by the rise in the temperature or the rise in the pH. The scale deposited in the portions cannot be removed even if the polarity of the electrode is reversed, and causes piping or the like to be clogged. If the cleaning solution is used, however, the scales can be simply removed.
The invention as set forth in the claim 22 is directed to a water treatment device comprising electrolyzing and sterilizing means, comprising an electrolytic tank to put water in and an electrode provided in the electrolytic tank in order to electrolyze the water, for pouring water into the electrolytic tank, energizing the electrode, and electrolyzing the water, to sterilize the water; a water treating path connected to a pool storing water for pouring the water in the pool into the electrolytic tank and returning to the pool the water in the electrolytic tank; current sensing means for measuring the value of current flowing through the electrode; conductivity measuring means for measuring the electrical conductivity of water; and scale adhesion judging means for judging how a scale adheres to the electrode on the basis of outputs of the current sensing means and the conductivity measuring means.
The invention as set forth in the claim 23 is the water treatment device as set forth in the claim 22, further comprising life judging means for judging the life of the electrode on the basis of the outputs of the current sensing means and the conductivity measuring means.
In the construction as set forth in the claims 22 and 23, it is possible to accurately judge the amount of the scale adhering to the electrode and the life of the electrode. The reason for this is that when a predetermined DC voltage is generally applied between the electrodes, the value of current flowing between the electrodes is proportional to the conductivity "sgr" of the solution supplied to the electrolytic tank. Consequently, the relationship of I=K"sgr" holds between the conductivity "sgr" and current I flowing between the electrodes, where K is a proportional constant.
The proportional constant K always assumes the same value if the electrode does not vary. Actually when the current is caused to flow through the electrode to continue electrochemical reaction, however, the surface of the electrode is covered with the scale or the like, the electrode corrodes, or a surface catalyst of the electrode is exhausted. Accordingly, the value of K is gradually decreased. Therefore, the value of K is always found by an operation, thereby making it possible to judge how the scale adheres to the electrode and judge the life of the electrode.
The invention as set forth in the claims 22 and 23 is for judging how the scale adheres to the electrode and/or the life of the electrode on the basis of such a principle.
The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.